Studies are examining the effects of adrenal steroids on the neurochemical adaptation of the brain to stress. Neurochemical studies of adenylate cyc lase activity and mRNA; CRF and vasopressin mRNA and peptide level; and tyrosine hydroxylase mRNA and enzyme level as they are influenced by stress and glucocorticoids. Studies of the mechanism of dendritic atrophy caused by glucocorticoids and stress, using serotonin and glutamate neurotransmitter receptor blocking drugs. Studies of the efficacy of antidepressant drugs on these same endpoints.